Treatment of butane



PatentedMay 9, 1944 UNITED s'rA'rEs "PATENT- orrics 2,348,100 4 ITREATMENT ornu'rann Vladimir N.- Ipatiefl' and Herman Pines, Chicago,

'IlL, assignors to Universal Oil Products Company, Chicago, 111., acorporation otl Jelawarev our co-pending application Serial No. 103,383filed September 30, 1936. This invention relates to the treatment ofbutane of normal or straight-chain structure.

In a more specific sense, the invention is concerned with a processwhereby normal butane is converted into isobutane, the process involvingthe use of special catalysts and particular conditions of operationwhich favor the isomerization reactions so that relatively high yieldsof the iso compound are produced.

Since the invention is concerned principally with the two i-carbon atomparaflln hydrocarbons and their transformation, one into the.

other, the following-table is introduced to indicate the structure andthe principal physical I characteristics of these two compounds:

Properties of butuhes Name I Structure B P" $513231" v C. ture, atmos C.pheres n-Butanm..- omcEcmcm--. +0.5 151 36 on; i-Butane- .\CH--CH;.-.10.s 134.5 p31 Butanes are produced in considerable quantities in theoil refining industry. They occur in substantial amounts in naturalgases (in which the normal compound usually predominates), in refinerygases which are evolved from crude pe- No Drawing. Application December28, 1940, I- Serial N0. 372,174

11 Claims. (Cl. 260683.5)

! This application'is a continuation-in-part oi of desirable startingcharacteristics according to seasonal demands.

The butanes at the present time bear a further important relationship tooil refining in'that their excess production is being utilized as asource of gasoline either by ordinary thermal cracking or by specialcatalytic dehydrogenation processes followed by polymerization in whichcatalysts may or may not be used. Investigations-have shown thatiso-butane is considerably more amenable to cracking anddehydrogenation, both with and without catalysts, than the normalcompound. Considering the corresponding mono-olefins, the normal butenesare considerably more difil'cult to polymerize, either thermally orcatalytically, than iso-butene,-and it is found also that the octenesrepresenting'the dimers of the isobuten'e are of higher antiknock valuethan those from n-butenes which holds also for the octanes produced byhydrogenation. It is, therepresent invention is especially concernedwith a process for accomplishing this object.

In one specific embodiment the present inven- \tion comprises thetreatment of normal butane troleum storage tanks, and in the primary'distillation of crudes, and they-are also present in considerablepercentages in the gases produced incidenta to cracking heavy petroleumfractions for the production of gasoline. In the case of crack gasmixtures the relative proportions of isoand normal butanes vary, but theratio of the iso to the normal compound is as a r'uleconsid- .erablyhigher than in natural gas.

Butanes may be considered as more or less marginal compounds in respectto their'desira-' other gasoline components to produce a gasoline forthe isomerization thereof into isobutane with catalyts comprisingessentially aluminum chloride and aluminum bromide along with minoramounts of hydrogen chloride and/or hydrogen bromide at temperatures andpressures adequate 'to efiect the desired isomerization to a substanofhydrogen chloride and hydrogen bromide added to,the reaction zoneandutilizing proper combinations of temperature and pressure, we havedetermined that normal butane may be isomerized to iso-butane topractically any desired extent, particularly when using hydrogen in thereaction zone to depress any desired side reactions.

As a rule,-temperatures of from 0 to C. will be employed and pressuresfrom about atmospheric'to" about 50 atmospheres. Using the pre- ,ferredcatalysts and selected conditions of tem-' perature and pressure it hasbeen found that it is possible to minimize undesirable side reactionsother than isomerl zation which otherwise results in the formation ofhydrogen and hydrocarbons of both higher and lower molecular weight thanthe desired isobutane.

The invention comprises the use of mixed aluminum chloride-aluminumbromide catalyst in any desired proportions either in granular form ordeposited upon granular supported materials. Aluminum bromide has beenfound to be generally a more powerful isomerization catalyst hydrogenchloride and hydrogen bromide in isomerization reaction zones. The useof hydrogen up to a critical amount depending upon the type of activityof the catalyst composite employed prevents undesirable side reactionswhile amounts greater than this tend to depress or retard theisomerization reaction itself.

The process of the invention may be operated under batch or continuousconditions. Batch operations may be conducted by separately addingaluminum chloride, aluminum bromide, hydrogen chloride and or hydrogenbromide and normal butane to a closed pressure container after which thecontainer is agitated or the contents stirred mechanically while thetemperature and pressure are maintained at anoptimum point, to produce agiven yield production of the iso compound, This type of operation isbetter adapted to small scale production, while plants of considerablecapacity are best operated in a continuous manner.

In continuous operations the butane may'be pumped through a tubularheating element at a 4 given temperature and pressure within theapproximate ranges previously specified and reaction brought, aboutalong the line of flow by the separate or joint injection ofproportioned amounts of aluminum chloride-aluminum bromide, hydrogenchloride and or hydrogen bromide. In the absence of moisture there willbe substantially no corrosion when using these catalyst composites.After passage through the heating element the reactants may be passed toenlarged insulated chambers for the completion of the desiredisomerization and the total products subsequently fractionated torecover catalyst and separate the normal and isobutanes, after which thenormal compound may be re-' cycled for further treatment. Unusedaluminum halides and hydrogen halides may also be recycled for furtheruse.

Continuous operations may also be conducted by passing normal butanemixedwith proportioned amounts of hydrogen chloride and or hydrogenbromide through beds of heated, granular catalyst, which may compriseany proportions of aluminum chloride and aluminum bromide alone orpreferably on relatively inert granular carriers. Among carriers whichare readily utilizable may be mentioned activated carbon, clays, fullersearth, alumina, bauxite silica alumina composites, diatomaceou's earthand in general, refractory materials of the porous adsorbent character.Treatment of the products of the isomerization reactions in these caseswill involve mere- In the preparation of granular catalysts com- Iprising aluminum chloride-aluminum bromide composites on supports, aconvenient method of preparation is to place a granular support such asactivated carbonin a rotatable pressure vessel along with the desiredamounts of aluminum bromide-aluminum chloride after which the pressurevessel is closed and hydrogen chloride and hydrogen bromide introducedunder pressure. The contents of the pressure vessel are then heated toan elevated temperature with or without the addition of hydrogen or somesubstantially inert gas until the granular particles of th; support areimpregnated with the mixed halides. In these operations of manufacture,it

' is generally preferable to employ temperatures of the order of from150 to 200 C. to insure proper distribution and penetration of thehalides on granular particles. Aluminum bromide melts at 97.5 C. andboils at 268C. while aluminum melts at 190 C. under 2.5 atmospherespressure and sublimes at 1"I8 C. at atmospheric pressure. In continuousoperations with granular supported catalyst composites prepared in thismanner, it is advantageous to employ sufllcient amounts of theproportioned metal halides to substantially saturate granular particlesat temperature and pressure of operation in order to get the maximumisomerizing'eflect from a given catalyst space.

In continuous operations it is comprised with? in the scope of theinvention to increase the temperature in reactors-as the granularcatalyst becomes spent or to increase the amount of hydrogen chlorideand/ or hydrogen bromide added,

each expedient tending to compensate for the loss in catalytic activity.

The following data are introduced to illustrate the character oi'theresults obtainable in the operation of the process of the invention butwithout the intention of unduly restricting its scope thereby: I

A mixture consisting of 80 mols of normal butane, 10 mols of hydrogen, 5mols of hydrogen chloride and ,5 mols of hydrogen bromide is passed overa granular catalyst consisting of percent by weight of granular aluminasupporting 15 percent by weight of substantially anhydrous aluminumchloride and 5 percent by weight of aluminum bromide at a, temperatureof C. and a pressure of 200 pounds per square inch. Under theseconditions, using a liquid space velocity of normal butane correspondingto 2 volumes of liquid per volume of catalyst space per hour, it isfound that there is a 40' percent conversion to iso-butane per passover, the catalyst, the ultimate yield 'of iso-butane obtained whenrecycling separated unconverted normal butane being 80 percent, the 20percent difference being due to side reactions resulting in a formationof lighter and heavier materials.

We claim as. our invention:

butane therefrom which comprises subjecting said normal butane tocontact with a catalyst comprising essentially aluminum chloride andaluminum bromide.

2. A process for the isomerization of normal butane to producesubstantial yields of isobutane therefrom which comprises subjectingbutane to produce substantial yields of. iso

2,348,700 said normal butane at'a temperature of from about zero toabout 150 Cato contact with a catalyst comprising essentially aluminumchloride and aluminum bromide.

3. A process for the isomerization of normal butane to producesubstantial yields of isobutane therefrom which comprises subjectingsaid normal butane at a temperature of from about zero to about 150 Chata pressure of.from about atmospheric to about "150 pounds per squareinchto contact with a catalyst comprising essentially aluminum chloride andaluminum bromide.

4. A process for the isomerizatlon of normal butane therefrom whichcomprises subjecting said normal butane mixed with proportioned amountsof hydrogen chloride and hydrogen bromide at a temperature of from aboutzero. to about 150 C. at a pressure of from about at- -mospheric toabout 750 pounds per squareinch to contact with a catalyst comprisingessentially a proportioned mixture of aluminum chloride and aluminumbromide. e

5. A process for the isomerization of normal butane to producesubstantial yields of isobutane therefrom which comprises subjectin saidnormal butane mixed with'proportioned amounts of hydrogen chlorideandhydrogen bromide at a temperature of from about zero to about 150 C. ata pressure of from about atmospheric to about 150 pounds per square inchto contact with a catalyst comprising essentially a proportioned mixtureofaluminum chloride and aluminum bromide, the ratio of said alumigrcaterthan 1. i

6. A process for the isomerlzation of normal butane to producesubstantial yields of iso- -butane therefrom which comprisessubiecting a-mixture of hydrogen, said normal butane and proportioned amounts ofhydrogenchlo- I ride and hydrogen bromide at a temperatureof from aboutzero to about 150 C. at a'pressure of from-about atmospheric to about'150 pounds P Square inch to contact with a catalyst comprisingessentially a proportioned mixture of aluminum chlorldeand aluminumbromide.

.7. A process for the isomerlzation of normalv butane to producesubstantial yields of isoa mixture 7 of hydrog n,v said normal butaneand proportlonedamolmts'of hydrogen chloride and hydrogen bromide at atemperature of from about zero to about 150 C. at a pressure of fromabout atmospheric .to about I50 pounds per square inch to contact with acatalyst comprls ing essentially a proportioned mixture of aluminumchloride and alumhiumbromide, the ratio of saidaluminum chloride andsaid aluminum bromide being greater than 1.

8. A proces for the isomerization ofnormal 'butane:to producesubstantial yieldsgof iso butane thereh-mn which comprises subjecting amixture of hydrosm'ss d no a butane 1 butane to produce substantialyields of isobutane therefrom which comprises subjecting, a mixture ofhydrogen, said normal butane 'num chloride and said aluminum bromidebeing butane therefrom which comprises subjecting and proportionedamounts of hydrogen chloride and hydrogen bromide at a temperature offrom about zero to about C. at a pressure of from about atmospheric toabout 759 pounds per square inch to contact with a catalyst comprisingessentially a granular composite of a relatively inert support and aproportioned mixture of aluminum chloride and aluminum bromide.

9. A process for the isomerization of normal and proportioned amounts ofhydrogen chloride and hydrogen bromide at a temperature of from aboutzero to about 150 C. at a pressure of from about atmospheric to about150 pounds per square inch to contact with a catalyst comprisingessentially a granular composite of a relatively inert support and aproportioned mixture of aluminum chloride and aluminum bromide,- theratio of said aluminum cb'loride and said aluminum bromide being greaterthan 1.

10. A continuous process for the isomerization 'of normal butane toproduce substantial yields of iso-butane therefrom which comprisessubjecting a mixture of hydrogen, butane and proportioned amounts ofhydrogen chloride and hydrogen bromide at a temperature of from aboutzero to about 150 C. at a pressure of from about atmospheric to about150. pounds per square inch to contact with a' catalyst comprisingessentially a granular composite of. a relatively inert support and aproportioned mixture of aluminum chloride and aluminum bromide,fractionating the products into a mixture comprising essentiallyhydrogen. hydrogen chloride and hydrogen bromide iso-butane, normalbutane, and spent granular catalyst, and recycling said mixtm-e and saidfractionated normal butane to further isomerization treatment.

11. A continuous process for the isomerization of normal butane toproduce substantial yields of iso-butane therefrom which comprisessubject ng a mixture of hydrogen, said normal butane and proportionedamounts of hydrogen chloride and hydrogen-bromide at a temperature "offrom about atmosphericto about 750 pounds per square inch to contactwith a catalyst com prising essentially a granular composite of arelatively inert support and a proportioned mixture of -aluminumchloride and aluminum bromide. the ratio 01' said aluminum chloride offrom about zero to about 150 C. at a pressure

